Error message for image conversion failure

When image conversion fails due to space constraints
on image_conversion_dir, log a straightforward error
message indicating this is the case:

"No space left in image_conversion_dir path
 (/var/lib/cinder/conversion) while fetching
 image 6261d1ec-2a15-4a68-977a-ea22ff342b74."

Change-Id: I4c4ca1bdcbb86739613d64997bbc78e3a72d570a

cinder/image/image_utils.py

@@ -25,6 +25,7 @@ we should look at maybe pushing this up to Oslo
 
 
 import contextlib
+import errno
 import math
 import os
 import re
@@ -33,13 +34,14 @@ import tempfile
 from oslo_concurrency import processutils
 from oslo_config import cfg
 from oslo_log import log as logging
+from oslo_utils import excutils
 from oslo_utils import fileutils
 from oslo_utils import imageutils
 from oslo_utils import timeutils
 from oslo_utils import units
 
 from cinder import exception
-from cinder.i18n import _, _LI, _LW
+from cinder.i18n import _, _LE, _LI, _LW
 from cinder import utils
 from cinder.volume import throttling
 from cinder.volume import utils as volume_utils
@@ -187,7 +189,18 @@ def fetch(context, image_service, image_id, path, _user_id, _project_id):
     start_time = timeutils.utcnow()
     with fileutils.remove_path_on_error(path):
         with open(path, "wb") as image_file:
-            image_service.download(context, image_id, image_file)
+            try:
+                image_service.download(context, image_id, image_file)
+            except IOError as e:
+                with excutils.save_and_reraise_exception():
+                    if e.errno == errno.ENOSPC:
+                        # TODO(eharney): Fire an async error message for this
+                        LOG.error(_LE("No space left in image_conversion_dir "
+                                      "path (%(path)s) while fetching "
+                                      "image %(image)s."),
+                                  {'path': os.path.dirname(path),
+                                   'image': image_id})
+
     duration = timeutils.delta_seconds(start_time, timeutils.utcnow())
 
     # NOTE(jdg): use a default of 1, mostly for unit test, but in

cinder/tests/unit/test_image_utils.py

@@ -15,6 +15,7 @@
 #    under the License.
 """Unit tests for image utils."""
 
+import errno
 import math
 
 import mock
@@ -24,6 +25,7 @@ from oslo_utils import units
 from cinder import exception
 from cinder.image import image_utils
 from cinder import test
+from cinder.tests import fixtures
 from cinder.tests.unit import fake_constants as fake
 from cinder.volume import throttling
 
@@ -275,6 +277,30 @@ class TestFetch(test.TestCase):
         (mock_fileutils.remove_path_on_error.return_value.__exit__
             .assert_called_once_with(None, None, None))
 
+    def test_fetch_enospc(self):
+        stdlog = self.useFixture(fixtures.StandardLogging())
+
+        context = mock.sentinel.context
+        image_service = mock.Mock()
+        e = IOError()
+        e.errno = errno.ENOSPC
+        image_service.download.side_effect = e
+        image_id = mock.sentinel.image_id
+        path = '/test_path'
+        _user_id = mock.sentinel._user_id
+        _project_id = mock.sentinel._project_id
+
+        with mock.patch('cinder.image.image_utils.open',
+                        new=mock.mock_open(), create=True):
+            self.assertRaises(IOError,
+                              image_utils.fetch,
+                              context, image_service, image_id, path,
+                              _user_id, _project_id)
+        error_message = ('No space left in image_conversion_dir path '
+                         '(/) while fetching image %s.' % image_id)
+
+        self.assertTrue(error_message in stdlog.logger.output)
+
 
 class TestVerifyImage(test.TestCase):
     @mock.patch('cinder.image.image_utils.qemu_img_info')